Large caliber guns of the kind of interest for present purposes generally include a frame which enables azimuth and elevation to be adjusted and which frame, during firing, is held stationary. Normally, the barrel of the gun is mounted for limited axial movement relative to the frame so that, upon firing, the gun barrel recoils and moves backward relative to the frame. Before the gun can be fired again, the backward movement must be stopped, the gun must be reloaded, and the barrel returned to its forward, firing position.
The firing of a gun releases a great deal of energy some of which inevitably appears as the kinetic energy of the rearward motion or recoil of the gun barrel and associated parts which move with the gun barrel. When referring to the gun barrel, hereinafter this generally refers to the barrel and all parts which move with the barrel, e.g. the gun barrel assembly. In order to stop the rearward motion of the gun barrel assembly, the kinetic energy must be dissipated and/or stored and/or utilized, and equipment for these purposes is normally provided. Such equipment may vary widely in kind and complexity. One arrangement includes a pair of hydraulic cylinders and pistons with one element of each, for example, the cylinders, fastened to opposite sides of the gun barrel while the other elements, in this case, the pistons, are fastened to the frame. Hydraulic circuitry connects the cylinders to an accumulator so that, during recoil, fluid from the cylinders flows to the accumulator thereby storing the energy of recoil. This equipment may be supplemented by snubbers such as springs, rubber bumpers, dash pots and the like. The stored energy may be used to reload the gun and/or to return it to its firing position.
Equipment such as that briefly described above has been widely used but has been subject to a number of disadvantages. It is highly desireable that the velocity of recoil, or backward movement of the gun barrel be within a predetermined range of velocity when the gun barrel reaches its "sear" position so as to establish the loading cycle as well as prevent damage to the snubbing device. Loading generally takes place simultaneously with the snubbing.
However, with the equipment used in the past this velocity has tended to vary widely because of the many variables involved. For example, different kinds of ammunition which may be used with a gun cause different recoil forces to be generated. Additionally, the amount of charge varies from unit to unit of ammunition of the same kind due to normal variations in the manufacturing process. The elevation of the gun barrel also affects the forces involved. A further complication is that sometimes the gun may be fired from "runout" where it has a forward velocity while at other times it may be fired from "battery" where the gun is stationary. Obviously, these two situations cause different forces to be exerted on the recoil pistons. Another related problem is that of controlling "runout" or the return of the gun barrel to its firing position in such a way that it will be moving at a preselected velocity when it reaches the firing position. This is necessary to establish a known initial velocity at the time of firing, so that the time of loading of the next round can be accurately set. Here again, variations in elevation cause variations in the forces which must be controlled.